[BEAM-656] Add support for side inputs/outputs to Java 8 lambdas in MapElements

• Type: Improvement
• Status: Open
• Priority: P3
• Resolution: Unresolved
• Component/s: sdk-ideas
• Assignee: Unassigned
• Reporter: Jani Patokallio
• Created: 21/Sep/16 05:34
• Updated: 03/Jun/22 16:17

Description

Currently there's no way to use side inputs or outputs within Java 8 lambdas and MapElements. It would be nice if you could do something like this:

PCollection<Integer> wordLengths = words.apply(
    MapElements.via((String word) -> {
      int sideInput1= [[[ GetSideInputHere(); ]]]
      [[[ SetSideOutputHere ]]] (sideInput1+word.length());
      return word.length();
    }).withOutputType(new TypeDescriptor<Integer>() {});